Solid state storage devices can shift over time. For example, memory cell leakage (often referred to as charge leakage), memory cell damage and other disturbances to memory cells can alter the read voltage levels of the memory cells. Thus, the read reference voltages can shift over time. If the read voltage level of a memory cell shifts past a read reference voltage, a data error occurs, as the value of the data read from the memory cell is different than the value of the data that was written to the memory cell.
In many flash memory systems, for example, the read reference voltages vary as a function of page number, where different page numbers require different read reference voltage values in order to reduce the bit error rate. A need exists for techniques for determining read reference voltages for a given page.